How Much Magnesium Per Day? Dosage by Age & Sex for Canada (2026)
Health Canada says adults need 400–420 mg of magnesium a day (men) or 310–320 mg (women), from food and supplements together. From supplements alone, stay at or under 350 mg a day, Health Canada’s upper limit. Many Canadian labels allow more: 5 of the 8 licences we read do.
A summary of Health Canada guidance and published research, not medical advice. Ask your doctor or pharmacist before taking magnesium if you have kidney disease or take prescription medicines.
Magnesium sold in Canada, matched to your dose
Each amount is the magnesium itself, from the product’s Health Canada licence.
- Buy on Amazon for Jamieson 100% Pure Magnesium Bisglycinate 100 mg
Our pick: 100 mg a day, bisglycinate only
Jamieson 100% Pure Magnesium Bisglycinate 100 mg CA$0.18 a capsule
NPN 80131651. Its licence says 1 capsule a day for adults. Sold by Amazon.ca.
- Check price for Nutritionn Magnesium Glycinate 200 mg
200 mg in one capsule
Nutritionn Magnesium Glycinate 200 mg
NPN 80137688, bisglycinate only. Its licence tells men to take 2 (400 mg), over the 350 mg limit; 1 stays under it.
- Check price for Natural Factors Magnesium Bisglycinate 200 mg Powder
A powder you stir into water
Natural Factors Magnesium Bisglycinate 200 mg Powder
NPN 80091128, bisglycinate only. 200 mg a 2.4 g scoop.
Other doses:
- Webber Naturals Magnesium Citrate 150 mg: 150 mg a capsule (citrate), CA$0.30 per 300 mg, the lowest cost per mg at list price.
- NOW Magnesium Citrate 200 mg: 200 mg a tablet (citrate). Its licence says 2 tablets (400 mg); 1 stays under the limit.
- Webber Naturals Magnesium Bisglycinate 200 mg: 200 mg a capsule; its licence lists bisglycinate and magnesium oxide.
- Pure Encapsulations Magnesium (Glycinate) 120 mg: 120 mg a capsule, bisglycinate only; its licence allows up to 4 capsules (480 mg).
- Natural Factors Magnesium 250 mg: 250 mg a caplet; its licence lists oxide with malate and glycerophosphate.
Costs are each brand’s own CAD list price, read October 15, 2026. Why these are our Canadian picks
How Much Magnesium Per Day? Health Canada’s Table
| Age | Men | Women | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Children 1–3 years | 80 | 80 | — | — |
| Children 4–8 years | 130 | 130 | — | — |
| Children 9–13 years | 240 | 240 | — | — |
| 14–18 years | 410 | 360 | 400 | 360 |
| 19–30 years | 400 | 310 | 350 | 310 |
| 31–50 years | 420 | 320 | 360 | 320 |
| 51 years and over | 420 | 320 | — | — |
These are the same numbers the US uses; both come from the 1997 North American intake review. The upper limit for magnesium from supplements is 350 mg a day from age 9, including pregnancy (65 mg for ages 1 to 3, 110 mg for ages 4 to 8). Health Canada’s footnote: The UL for magnesium represents intake from a pharmacological agent only and does not include intake from food and water.
What Canadian Labels Tell You to Take
Every licensed product has a dose approved by Health Canada, listed in the Licensed Natural Health Products Database. We looked up the daily dose on the licence of each product here. Five of eight allow more than the 350 mg upper limit.
| Item | Value (mg) |
|---|---|
| Jamieson 100% Pure Magnesium Bisglycinate | 100 mg |
| Nutritionn Magnesium Glycinate | 400 mg |
| Natural Factors Magnesium Bisglycinate | 200 mg |
| Webber Naturals Magnesium Bisglycinate | 200 mg |
| Webber Naturals Magnesium Citrate | 450 mg |
| NOW Magnesium Citrate | 400 mg |
| Pure Encapsulations Magnesium (Glycinate) | 480 mg |
| Natural Factors Magnesium | 500 mg |
That is not a mistake on the label. Health Canada’s monograph allows adult products up to 500 mg a day; above 350 mg the label must name a specific use and carry the warning When using this product you may experience diarrhea
. If you follow a label to 400 or 500 mg, you are over the upper limit, where loose stools are the usual result. Taking part of the serving keeps you under it.
Understanding Elemental vs Compound Weight
On a Canadian label the medicinal ingredient line reads like “Magnesium 200 mg (magnesium bisglycinate)”. The 200 mg is the magnesium itself; the word in brackets is the source. The front of the bottle may show the whole compound: 1,000 mg of magnesium bisglycinate holds only about 140 mg of magnesium. If the brackets list two sources, such as bisglycinate and oxide, part of your dose is oxide.
Amounts Used in Published Trials
These are amounts researchers gave, not advice. Several are above the 350 mg limit and were given under supervision.
| Goal | Amount studied | What was found |
|---|---|---|
| Sleep | 320–729 mg (3 trials, older adults); 250 mg as bisglycinate (2025) | Fell asleep about 17 minutes faster, low-quality evidence (Mah 2021); a small effect in the 2025 trial (Schuster 2025) |
| Night-time leg cramps | 226 mg as magnesium oxide (Barna 2021) | A small drop in cramp count against placebo; a Cochrane review found no clear benefit for older adults with general cramps |
| Constipation | Magnesium oxide | 68% improved on oxide vs 19% on placebo in 2 trials (van der Schoot 2023) |
When to Take Magnesium, and What to Space It From
None of the Canadian licences we read carries a medicine warning, so here is what the US NIH says:
- Antibiotics: take tetracyclines (such as doxycycline) or quinolones (such as ciprofloxacin) at least 2 hours before or 4 to 6 hours after magnesium (NIH).
- Osteoporosis drugs (bisphosphonates such as alendronate): take them at least 2 hours apart from magnesium (NIH).
- If you have kidney disease, ask your doctor before you take magnesium. Weak kidneys cannot clear the extra, so it can build up (NIH).
- Heartburn pills (PPIs such as esomeprazole or lansoprazole), taken for a year or more, can lower magnesium. In about 1 in 4 of the cases FDA reviewed, supplements did not raise it and the PPI had to be stopped (NIH).
Any time of day works. Take it with food if it upsets your stomach, or split the dose between two meals.
Frequently Asked Questions
How much magnesium should I take per day in Canada?
Health Canada’s recommended amounts, from food and supplements together, are 400 mg (men 19 to 30) or 420 mg (31 and over), and 310 mg (women 19 to 30) or 320 mg (31 and over). From supplements alone, stay at or under 350 mg a day.
Why can a Canadian label tell me to take more than 350 mg?
Health Canada’s monograph lets adult products give up to 500 mg a day. Above 350 mg the label must state a specific use and warn “When using this product you may experience diarrhea”. The 350 mg upper limit is the level above which diarrhea becomes more likely.
Does food count toward the 350 mg limit?
No. Health Canada’s table says: “The UL for magnesium represents intake from a pharmacological agent only and does not include intake from food and water.”
How much magnesium during pregnancy?
Health Canada’s table gives 400 mg (18 and under), 350 mg (19 to 30) and 360 mg (31 to 50) a day in pregnancy, from food and supplements. The supplement limit stays 350 mg. Ask your prenatal provider first; many prenatal vitamins already contain some.
Is the dose on the front of the bottle the magnesium?
Not always. On a Canadian label, the medicinal ingredient line gives the magnesium and its source in brackets. The front may show the whole compound: 1,000 mg of magnesium bisglycinate holds only about 140 mg of magnesium.
What doses did the sleep studies use?
Three small trials in older adults used 320, 500 and up to 729 mg a day; a 2025 trial used 250 mg as bisglycinate. Two of those are above the 350 mg limit. These are amounts studied, not advice.
Related Guides
- Best magnesium supplement in Canada · magnesium forms compared
- Magnesium and sleep · side effects (research that applies anywhere)
Sources
- Health Canada. Dietary Reference Intakes tables: reference values for elements (page dated November 19, 2025).
- Health Canada. Multi-Vitamin/Mineral Supplements monograph (June 26, 2026).
- Health Canada. Licensed Natural Health Products Database: product dose records for each NPN on this page, read October 15, 2026.
- US NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (medicines).
- Mah 2021, PubMed 33865376; Schuster 2025, PubMed 40918053; Barna 2021, PubMed 34719399; van der Schoot 2023, PubMed 37243443.